<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>   
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<style type="text/css">
	.banner {
		border: 1px solid red;
		width: 100%;
		height: 80px;
	}
	
	.nav {
		border: 1px solid blue;
		width: 200px;
		height: 680px;
		float: left;
	}
	
	.main {
		border: 1px solid green;
		width: 100%;
		height: 680px;
	}
	
	.foot {
		border: 1px solid yellow;
		width: 100%;
		height: 30px;
	}
</style>
</head>
<body>
<c:if test="${not empty username }">
	<div class="banner">
		<%@ include file="top.jsp" %>
	</div>
	<div class="nav">
		<%@ include file="nav.jsp" %>
	</div>
	<div class="main">
		<jsp:include page="main.jsp"></jsp:include>
	</div>
	<div class="foot">
		<%@ include file="concat.jsp" %>
	</div>
</c:if>

<c:if test="${empty username }">
	<c:redirect url="login.jsp"></c:redirect><%--等价于:response.sendRedirect()方法 --%>
</c:if>
</body>
</html>